Interlocking wooden mat roadway

Abstract

An interlocking wooden mat assembly for roadways in undeveloped areas comprises a three layered lamination of substantially parallel and closely spaced wooden planks forming each layer, which assemblies are rectangular and interlock along one of the longer sides. Selected planks of the bottom layer are offset longitudinally and extend beyond the intermediate layer at one end to provide a male extension on one end and a female recess at the other end. The planks of the bottom layer lie parallel to each other along the shorter dimension of the rectangular mat. The planks of the intermediate lie parallel to each other along the longer dimension of the rectangular mat and terminate at the edges of the rectangle. The top layer has planks extending parallel to each other and to the bottom planks along the shorter dimension of the rectangle comprising two groups of planks spaced toward the edges of the rectangle with the intermediate portion of the intermediate layer of planks being uncovered. The two groups of planks in the top layer are separated sufficiently to provide spaced tracks for the tires of a truck of other motor vehicle riding thereon, each group having a centrally located space wide enough to receive another plank of the same size. Extra planks are secured in those centrally located spaced and overlapping adjacent mat assemblies to secure such assemblies together as a roadway. Each mat assembly may have loops of cable for lifting and transporting.

While this invention has been described fully and completely with special emphasis upon a preferred embodiment, it should be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described herein. 
     
       1. A laminated wooden mat section of at least three ply construction adapted to be secured in interlocking relation to other like mat sections for constructing roadways in underdeveloped areas to be driven upon by the wheels of a motor vehicle, said mat section being of rectangular shape with a shorter side and a longer side at least 50% longer than said shorter side and comprising   an intermediate layer of closely spaced planks of predetermined width and of substantially equal length extending parallel to each other for the length of the longer side of said rectangular shape from one edge to the other thereof,   a bottom layer of substantially parallel wooden planks of predetermined width and of substantially equal length corresponding to the length of the shorter side of said rectangular shape, secured to said intermediate layer of planks at right angles thereto by nailing, with the ends thereof secured to the outermost planks of said intermediate layer to define said rectangular shape,   at least one plank of said bottom layer being longitudinally offset to provide a male extension at only one end and a female recess only at the other end of said bottom layer,   a top layer of substantially parallel wooden planks of predetermined width and of substantially equal length corresponding to the length of the shorter side of said rectangular shape, secured to said intermediate layer of planks at right angles thereto by nailing,   said top layer comprising two groups of closely spaced planks, each group of planks being of sufficient width and spaced one group from the other a sufficient distance to provide parallel tracks for the wheels of a motor vehicle when said mat sections are assembled into a roadway,   at least one of said top layer groups of planks having an internal longitudinal space of substantially the width of one of said planks,   said layers being securely attached together at common overlapping intersections, and   said bottom layer male extensions being adapted to fit and be removably secured in said female recess on an adjacent mat by being lowered into position for assembly along the longer edge of said rectangular shape with the edges and ends, respectively, of adjacent mats being in a straight line and said groups of top layer planks being aligned to define said parallel vehicle tracks, said mat sections being substantially lighter in weight than mats having closely spaced planks on each of the layers thereof and being constructed to permit a vehicle to move along a previously laid mat while laying the next mat in the roadway being assembled.   
     
     
       2. A mat section according to claim 1 in which said bottom layer of shorter planks has one plank at each end and at least one centrally disposed plank longitudinally offset to provide male extensions beyond said intermediate layer a distance of approximately the width of one of said intermediate layer planks at one end and to provide female recesses of like size at the other end.   
     
     
       3. A mat section according to claim 1 including a longitudinally extending tie-in plank of predetermined width adapted to be removably secured by nailing in said internal longitudinal space in one of said top layer groups of planks and having a length sufficient to fit in said internal longitudinal space in one of said top layer groups of planks on an adjacent mat section and be secured by nailing to releasably interlock adjacent mat assemblies together.   
     
     
       4. A mat section according to claim 1 in which said intermediate layer of longer planks has one end plank laterally offset to provide a male extension beyond the side of said rectangular shape a distance of approximately the width of one of said planks at one end and to provide a female recess of like size at the other end to permit side-to-side assembly of said mats into a double-wide roadway section.   
     
     
       5. A mat section according to claim 1 in which the planks of each of said layers are composed of road grade lumber.   
     
     
       6. A mat section according to claim 1 in which said planks are securely attached together at common overlapping intersections by nails. 
     
     
       7. A mat section according to claim 1 in which the longer side of said mat section is substantially twice the length of said shorter side.   
     
     
       8. A mat section according to claim 1 in which said bottom layer has one plank at each end and at least one centrally disposed plank longitudinally offset to provide male extensions beyond said intermediate layer a distance of approximately the width of one of said intermediate layer planks at one end and to provide female recesses of like size at the other end, and   said intermediate layer has one end plank laterally offset to provide a male extension beyond the side of said rectangular shape a distance of approximately the width of one of said planks at one end and to provide a female recess of like size at the other end to permit side-to-side assembly of said mats into a double-wide roadway section.   
     
     
       9. A mat section according to claim 8 including a longitudinally extending tie-in plank adapted to be removably secured by nailing in said internal longitudinal space in one of said top layer groups of planks and having a length sufficient to fit in said internal longitudinal space in one of said top layer groups of planks on an adjacent mat section and be secured by nailing to releasably interlock adjacent mat assemblies together.   
     
     
       10. A plurality of mat sections according to claim 1 assembled with the male extensions on one fitting the corresponding female recesses on an adjacent one and nailed to the adjacent layer thereof and having longitudinally extending tie-in planks nailed in said internal longitudinal space in one of said top groups of planks to interlock adjacent mat assemblies releasably together.   
     
     
       11. A plurality of mat sections according to claim 4 assembled in both side-to-side and end-to-end relation with the male extensions on one fitting the corresponding female recesses on an adjacent one and nailed to the adjacent layer thereof and having longitudinally extending tie-in planks nailed in said internal longitudinal space in one of said top groups of planks to interlock adjacent mat assemblies releasably together.   
     
     
       12. A mat section according to claim 1 including means secured thereon for lifting and transporting the same.   
     
     
       13. A mat section according to claim 12 in which said lifting and transporting means comprises at least one cable loop secured adjacent to the center of gravity of said mat section around selected planks of said bottom layer.   
     
     
       14. A plurality of mat sections according to claim 13 assembled with the male extensions on one fitting the corresponding female recesses on an adjacent one and nailed to the underlying layer thereof and having longitudinally extending tie-in planks nailed in said internal longitudinal space in one of said top groups of planks to interlock adjacent mat assemblies releasably together.   
     
     
       15. A mat section according to claim 4 including means secured thereon for lifting and transporting the same.   
     
     
       16. A mat section according to claim 15 in which said lifting and transporting means comprises at least one cable loop secured adjacent to the center of gravity of said mat section around selected planks of said bottom layer.   
     
     
       17. A plurality of mat sections according to claim 16 assembled with the male extensions on one fitting the corresponding female recesses on an adjacent one and nailed to the underlying layer thereof and having longitudinally extending tie-in planks nailed in said internal longitudinal space in one of said top groups of planks to interlock adjacent mat assemblies releasably together.   
     
     
       18. A mat section according to claim 1 in which said shorter side is about 8 ft. and said longer side is about 12-16 ft. in length.